Particle accelerators utilize a fundamental rf power and frequency to accelerate the particle beam. As the accelerator operates, the beam stimulates the production of rf energy at different frequencies than those used to power the device (referred to as higher order modes). The generation of such higher order modes can interfere with the operation of the accelerator and also generate heat within the accelerator resulting in “missteering” of the beam. It is therefore desirable and necessary that such higher order rf frequencies and the heat generated thereby be extracted from the accelerator. The thermal conductance for obtaining the necessary heat extraction has been calculated and determined to be greater than 20 mW with less than 0.2 T at >5° K. Whatever mechanism is used to extract this heat, useful rf transmission line characteristics on the order of 50 ohms (to assure higher mode rf frequency extraction), vacuum hermeticity and mechanical integrity under cryogenic conditions must be maintained.
While rf feedthrough devices are known in the art, (such devices are commercially available from Amphenol, 358 Hall Ave., Wallingford, Conn. 06492) none to our knowledge, are capable of providing the high thermal conductance necessary to meet the thermal extraction needs just described.
It would therefore be highly desirable to provide a cryogenic vacuum rf feedthrough device that was capable of meeting these requirements in order to better stabilize the operation of particle accelerators.